Experimental Physics and
Industrial Control System

"Owens, PH \(Peter\)" <[email protected]> · Fri, 2 Nov 2007 14:35:39 -0000

If you were going to do it that way you could use the PHAS
field to ensure that the calc records were processed later
in the scan than the inputs - thus processed up-to-date values.

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Heinrich du Toit
> Sent: 02 November 2007 14:02
> To: Eric Norum; EPICS tech-talk
> Subject: Re: lexical analyzer for .db?
> 
> 
> Hi
> 
> Thanks for all your help
> 
> Wonder why the FLNK isn't a direct DB link then if possible? (e.g. 
> record inside same IOC)
> Does the fanout do it differently?
> 
> What would you say about the idea of just putting all the 
> inputs on SCAN 
> = .2 second
> and then all the calc(out) rule records also on .2seconds SCAN ?
> 
> The way I see it a calc record can then never work with a value older 
> than .4 seconds... which is fine for the system I think.
> 
> Can maybe just FLNK or fanout the critical stuff then
> 
> -H
> 
> 
> Eric Norum wrote:
> > On Nov 2, 2007, at 8:30 AM, Ned Arnold wrote:
> >
> >>
> >> You may be able to eliminate the fanout records by careful 
> design of 
> >> forward links and/or input link flags (PP, CP, etc).
> >>
> >> For example, if the input record's forward link field 
> referenced the 
> >> calc record and the calc record's forward link field 
> referenced the 
> >> calcout record, all would process each time the input record 
> >> processed ... without a fanout.
> >>
> >
> > Don't take this technique to extremes, though.  I recall 
> helping Steve 
> > Shoaf diagnose problems with his database for a video switching 
> > system.  The database contained 128 records FLNK'd together.  This 
> > caused very weird IOC faults that we finally realized were 
> caused by 
> > stack overflow of the task processing the records -- 128 recursive 
> > calls to the record processing routine forced the task 
> stack pointer 
> > past the end of the stack space.
> > --Eric Norum <[email protected]>
> > Advanced Photon Source
> > Argonne National Laboratory
> > (630) 252-4793
> >
> >
> 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System